Background: Rodent models are a very helpful tool to investigate immunological mechanisms in allograft rejection. The aim of this study was to compare two different immunodeficient recipients in a humanized mouse model of arterial xenotransplantation in terms of reconstitution of the human immune system and rejection of the arterial graft. Methods: Side branches of human mammary artery were transplanted as infrarenal aortic interposition grafts into C.B-17-SCID beige and C57BL/6-Rag2γ/γγcγ/γ recipients. 7days after surgery mice were reconstituted with 5×107 human peripheral blood mononuclear cells (hu PBMCs) and 30days after reconstitution mice were sacrificed and histologic analysis was performed. Peripheral blood and splenocytes were investigated by FACS and ELISA analysis to ensure engraftment of human CD45+ cells. Results: Transplant arteriosclerosis developed in non-PBMC-reconstituted C.B-17-SCID beige mice (intimal proliferation: 36.31±4.37%), but significantly less in C57BL/6-Rag2γ/γ γcγ/γ recipients (intimal proliferation: 12.26±5.21%). After reconstitution with 5×107 unfractionated human PBMCs both mouse strains showed intima proliferation 30days after reconstitution (C.B-17-SCID beige: 28.49±7.95% and C57BL/6-Rag2γ/γ γcγ/γ: 44.58±11.08%). Whereas only very few human CD45+ cells were found in mouse blood and spleen of C.B-17-SCID beige mice, C57BL/6-Rag2γs/γ γcγ/γ mice revealed a reliable reconstitution. In addition, levels of human IgG and IgM within the peripheral blood were markedly higher in C57BL/6-Rag2γ/γ γcγ/γ recipients. Conclusion: In this study we can show, that the use of C57BL/6-Rag2γ/γ γc/γ mice may be advantageous compared to C.B-17-SCID beige recipients in a humanized mouse model of vessel transplantation.